Rapid increases in the prevalence and severity of obesity in the pediatric population will soon cause an increase in the incidence rate in many diseases associated with obesity in adulthood. Although obesity in youth is associated with adult obesity and obesity-related morbidity, little is known of the specific contribution of obesity at different points in childhood. Related phenomena, such as early maturation and accelerated growth, may also affect later health but have rarely been explored. This project will examine the impact of growth dynamics, with primary focus on incident obesity in childhood, adolescence and adulthood, and on all-cause and cause-specific mortality. A retrospective cohort study will be conducted of 1,842 subjects originally studied in the 1920s and 1930s near Boston as a part of the Third Harvard Growth Study. This early growth study represents one of the largest studies of physical growth ever undertaken. The annual anthropometric measurements obtained over 12 years will allow characterization of onset of overweight and obesity, incremental height and weight velocity, and maturational timing. Additional follow-ups of this cohort, conducted in 1968 and 1988, will provide information on adult weight status. This information will be related to survival and to cause of death from death certificates. It is hypothesized that obesity-related mortality is greater for childhood-onset and adolescent-onset compared to adult-onset overweight. It is also hypothesized that accelerated growth and early maturation further increase mortality risk. The investigators state that the proposed study is exceptional because childhood and adolescent growth data were carefully collected and the follow-up period was long. They point out that no other comparable data on a community-based sample in the U.S. exists, and that together, the early growth, adult follow-up, and mortality data are uniquely suited to characterize the relationship of the timing of overweight onset and other growth characteristics to all-cause and cause-specific mortality.